Manufacture granular particles are conventionally used as carriers for agricultural chemicals such as herbicides, plant growth regulators, fertilizers, etc. Various different types of granules are currently used for such applications. Patents disclosing granules include the following.
U.S. Pat. No. 5,019,564 discloses granules formed by the agitated agglomeration of slurries containing plant fibers and mineral fillers. These granules are utilized as carriers for biologically active chemical agents.
U.S. Pat. No. 5,078,779 discloses binder compositions that include reactive carbonates and reactive sulfates in combination with silicate strengthening agents and water-dispersing agents. These binders are used to carry ammonium sulfate fertilizers.
U.S. Pat. No. 5,242,690 discloses granular carrier compositions that include grain dust and a binder of calcium or sodium lignosulfonate, the compositions being useful as carriers for biologically active chemical agents.
U.S. Pat. No. 6,613,138 B2 and U.S. Pat. No. 6,231,660 B1 disclose granules that include one or more mineral components, one or more “light weight additives”, and one or more water soluble binders. These patents teach that the lightweight additives should be a non-fibrous material, because fibrous material can adversely impact the dispersibility and the flow characteristics of the finished granular substrate. The terminology “light weight additive” is vague. However, the patent provides some idea of what is meant by that terminology: “The light weight additives are preferably selected from the group consisting of expanded silica, fly ash, hydrated lime, wheat flour, wood flour, ground wheat straw, cellulose and soy flour.” U.S. Pat. No. 6,231,660, column 4, lines 33-36; 6,613,138, column 4, lines 46-49. The patentee explains what “wood flour” involves in the following words: “A preferred embodiment includes the use of wood flour resulting from finely milled wood particle board. The wood particle board contains approximately 10 wt % of a urea-formaldehyde resin. Another preferred embodiment includes the use of wheat straw flour resulting from finely milled wheat straw particle board. The wheat straw particle board contains a diphenylmethane diisocyanate resin.” U.S. Pat. No. 6,613,138, column 4, lines 40-46; 6,231,660, column 4, lines 52-58. The Examples in the patent disclose as binders brewers condensed solubles, calcium lignosulfonate, cane molasses, beet syrup, beet molasses, hydrolyzed collagen, soy solubles, whey, sodium carbonate lignin, protein amino acids, hemi-cellulose extract, sodium carboxymethyl cellulose, corn starch mixed with sodium carboxymethyl cellulose, and Baka-Snak.
There is an unmet need for carrier granules that will better satisfy the needs of industry. In particular, there is a need for small, light granules, having particles in the size range 10/40 Mesh and weighing approximately, for instance, around 28 pounds per cubic foot. The carrier granules should also have a Resistance to Attrition rating of greater than 95%. While some of these characteristics are found in some currently available granules, we are unaware of any carrier granules that provide all of these characteristics at the same time. A purpose of this invention is to provide carrier granules having particles in the size range 10/40 Mesh and weighing on the order of magnitude of 28 pounds per cubic foot and having a Resistance to Attrition rating higher than 95%.